Ideal Encoder Wood CNC Router

[justCNCit]

Hi I know this question probably comes up alot. Please tell me if you know what is the most recommended encoder to use with a Mach 3 stepper setup. 400oz in motors.

Also, would a breakout board be required or any outside wiring of components be needed or is there a possibility of plug and play. Thanks, also I realize that this subject will probably require alot of research before anything is bought, thanks for any and all input.

[epineh]

Stepper systems don't usually use encoders, they are open loop meaning the controller does not know if the motors have stalled.

Servo's use encoders to monitor position but that is a whole different story.

The closest thing I know of for a plug and play system would be the new Gecko G540 drive package :

http://www.geckodrive.com/product.aspx?c=3&i=14469

I don't have any affiliation with Gecko, just trying to help out. You will have to work out if the G540 can run your motor's, I think they are rated to 3.5 amps.

Good luck !

Russell.

[justCNCit]

I realize steppers don't usually use encoders, but for my machine there will be a dual Y axis drives (that is, 2 motors driving the Y axis on each side).

If one lost steps, it could do some damage. The setup I am currently using is a 4 axis Xylotex drive box with 4 (using 3) steppers 400 oz in.

[vger]

JustCNCit, I just recently finished a small (24" X 24" X 8") router table that uses small nema 23 steppers. I don't have the specs on the motors but am running them at .6 amps from the drives. I am driving the Y axis with a single screw (1/2 10 acme) centered under the table. Works well as long as I stay below about 80 IPM. Dual driving with 2 steppers and keeping them sync'd will be a bit difficult I think.

If you use encoders that have say 2000 PPR then you will get 10 pulses for every full step. Keep in mind that each time you step, the motor will over shoot just a bit and "ring" at it's natural resonance. Take a look at this page....
http://www.euclidres.com/apps/steppe...r/stepper.html

You may be better off using a single stepper and a belt (timing belt) to run the second screw...

Just my opinion
Steve

[justCNCit]

i was running this machine for a while and didn't notice any missed steps till the higher RPM when the resonant frequency kicked in and it was obvious.

I know the two motors won't run perfectly in sync but the question probably then is how much difference is there. Guessing nobody has done this. Was thinking of using encoders to lock them together and also adding counterweight dampeners to the steppers to add some stability.

Trying to avoid the belt approach.

[ger21]

Originally Posted by justCNCit Guessing nobody has done this.

Are you using Mach's slaving function? Lots of people are using it to drive both sides of a gantry. Unless you lose steps, then yes, they should stay perfectly in sync. Or at least awfully close.

You can get an encoder interface board and plugin from www.rogersmachine.net

[justCNCit]

I've read over their website, seems like a good product. Though is may not be the ideal place to ask these questions, I was wondering if Mach 3 would not only be able to stop axis but spindle as well if the encoders reported a big enough position loss.

I'll probably email them but they said there's 4 relays built into the board, I assume the relays are for limit/home switches?

thanks for the link.

ps. I run Mach 3 on a laptop PC (800 mhz P3 I believe)